Magnetism in a a wire and its effect on a metal ball

Like this? Not exactly a metal ball, but.........

well it could be.

I was thinking of putting a lot of wires under a table, putting a metal ball and the table and make it move (changing the current in the wires).

I was wondering if it was possible. For example I dont know if putting current in a wire will attract the ball or repulse it.

Take a quick look at the solenoid valve in your dishwasher. It has the answers.

Hi Mark, (Sorry for the poor presentation of this post, but I am writing from Google Chrome, and it doesn't work will with the CR4 website.) In fact, any current through any conductor will generate a magnetic field in a predictable way (aside from superconductors and very low temperature conditions of which I know little about), so the issue is not IF a magnet field is there, but HOW STRONG it will be. That is a function of the current, so the real issue is how much current can the conductor handle? If you listen to an arc welder when working, you will hear the coils inside trying to rip themselves apart, because of magnetism. If you watch any "loose" wiring of some quick-discharge system, you'll see them move and twitch because of the magnetism. This same phenomena is what makes motors "mote" and speakers "speak". For a single conductor to move a iron or steel ball PERCEIVABLY (it will always move it, but maybe not enough to notice) depends also on the distance the ball is away from the wire. Magnetic fields diminish rapidly with distance, so if you're trying to move a "heavy" ball from a few inches, you'll need a lot of power, and a large conductor. There are some simple experiments you can do to show the magnetic field ... if you're interested, reply to me and I'll give you some ideas. Kind regards ...

Thanks for your answer.

In fact I am currently having a look at micro-systems (no larger than 100 microns) object that people make move on really small surfaces. For example, here is a picture of an object that moves with the current induced in the electrodes (maybe the picture will explain better):

But I was thinking, considering the sizes in here that maybe we could just use magnetic fields of wires to make a ball move and it would be much easier. There I have to check the feasibility questions. I have found for example the equations to find the magnetic field as a function of the current and the distance.

But what I have really trouble with is the direction the ball is going to move...

Hope I was clear enough.

Thank you

Hello Mark,

From what I can see in your diagram, there is no induced current, so this is not a magnetic effect, and because of the dimensions involved, I'm not sure how to call it.

To give you some answer, however, if you look at this diagram, it may give some idea of how things MIGHT work given two conductors, and a ferrite ball.

In this cross-section, if you can imagine a direct current is induced in the left conductor, a magnetic field is present around that conductor, and the ferrite ball would move toward the center of that conductor. Switch off that current, and pass a direct current through the other conductor, and the ferrite ball would move toward the center of that conductor ... (BTW, line up a series of conductors, and switch them in a progressive sequence, and you have the principal of a rail gun).

Of course, Mark, all this is great in theory, but there are huge variables: Dimension, Mass, Coefficient of Friction of the parts in contact, the Current, the Conductor Materials, and the Frequency of the current being switched. The theory is sound, but making something actually work requires a lot more information, and likely some experimentation.

Kind regards ...

I am not sure if I did interpret your question in the correct manner, but you might possibly want to get a little bit more familiar with the phenomenon of "electromagnetic levitation". You can generate a magnetic field strong enough to lift (= levitate) for example a sample of a metal and, by modifying the field, also make the sample move. This principle has successfully been used for a number of material experiments performed during some Space Shuttle flights. A description of the levitation facility can be found here: http://dspace.mit.edu/bitstream/handle/1721.1/32164/33329336.pdf?sequence=1

I am sure that there should also be some movies taken during the experiments availabel on the internet, but I did not "google" for them.

regards nudnik